EMI Standard Compliance of Three-Phase Buck Type PFC Rectifier for Application in Aircraft

Aircraft's electrical systems operate at a fundamental frequency of 400 Hz, and it is important to test the compliance of power converters with the existing EMI standards. This paper investigates the application of three phase buck type rectifier in aircrafts and its compliance with the MIL-STD-461G. Due to control simplicity, high efficiency and high-power density, Swiss rectifier topology is chosen for this study. A complete simulation model of the rectifier including standard line impedance stabilization network (LISN) and high frequency filter is developed for evaluating the quality of input current. For high power density and high efficiency, a cascaded two-stage LC filter with parallel R-L damping is chosen to remove the high frequency ripple from input current. Harmonics in the current are calculated by following the regular procedure given by the standards. Simulation results under various operating conditions revealed that this rectifier comply with MIL-STD-461G subsection CE102 as it draws the input current with very low THD (< 5%) and high frequency harmonics are reduced well below the standard limits by a LC filter. However, glitches in input current at phase crossings and impedance of LISN introduce high harmonics near 10 kHz, which exceeds the standard limit values. Hence, Swiss rectifier with standard operation does not comply with MIL-STD-461G subsection CE-101.